Nonaqueous lubricating composition for nylon tire cord yarn



y 7, 1969 F. H. COATS, JR 3,446,734

NONAQUEOUS LUBRICATING COMPOSITION FOR NYLON TIRE CORD YARN Filed Jan. 18, 1967 INVENTOR FRED HADEN COATS, JR.

BY M4 ATTORNEY United States Patent US. Cl. 2528.8 9 Claims ABSTRACT OF THE DISCLOSURE A nylon yarn lubricating composition of 70 to 97 parts of a polyoxypropylene compound of 10 to 20 recurring units and capped by an alkyl or acyl group of l to 4 carbon atoms, 3 to 30 parts of a non-ionic surface-active condensate of ethylene oxide and up to parts of an antioxidant for the polyoxypropylene compound.

This application is a continuation-in-part of my earlier application Ser. No. 476,349, filed Aug. 2, 1965, now abandoned.

Industrial yarns are commonly manufactured using hot processing conditions and thus lubricating compositions applied to those yarns must meet the requirements imposed by a thermal environment. Unlike the situation for textile yarn lubricants, which must be easily removed from the yarn as in a scouring operation, lubricants for tire yarns remain on the yarn during the complete processing sequence and continue to function during the formation of the cords and indeed throughout the useful life of the'tire. By way of example, tire yarn lubricants must contribute to a high adhesion level and provide a pronounced resistance to flex fatigue in addition to functioning adequately during preparation of the yarn.

It is, therefore, the principal object of this invention to provide a tire yarn lubricating composition which will lead to high-temperature processing continuity and yield nylon tire cords having excellent adhesion to rubber and a high resistance to flex fatigue.

An additional object of the invention is to provide a process for producing nylon cord yarn having a finishing lubricant thereon.

A further object is to provide tire cord containing a lubricant finish thereon, the cord possessing excellent adhesion to rubber and a high resistance to flex fatigue.

These and other objects are attained in the present invention by using, in nylon cord production, a non-aqueous lubricating composition composed, by weight, of 70 to 97 parts of a polyoxypropylene compound of the formula R(OC H OR wherein R and R are selected from the class consisting of alkyl and acyl groups having 1 to 4 carbon atoms, and x has an average value of about to about 20, 3 to 30 parts of a non-ionic surface-active condensate of ethylene oxide and up to 5 parts of an antioxidant for the polyoxypropylene compounds. The use of the antioxidant is desirable, though optional. By applying .this composition as a spin finish to nylon yarn in an amount of about 0.5 to about 3.0 percent by weight, based on the weight of the resulting yarn, high temperature processing continuity is achieved and a yarn results that, in use as tire cord or the like, is characterized by having excellent adhesion to rubber and high resistance to flex fatigue.

The polyoxypropylene compounds useful in the invention are diethers, diesters, ether esters, or mixtures of two or more of the foregoing, of polyoxypropylene glycols having an average of about 10 to 20 oxypropylene groups. The alkyl radical of a terminal ether group is a ice saturated hydrocarbon radical having from 1 to 4 carbon atoms in its chain. The chain may be straight or branched. In those compounds where a terminal group is an ester group, it is derived from a straight or branched-chain organic monocarboxylic acid in which R" of the acyl group R" CO is a saturated hydrocarbon radical of 1 to 3 carbon atoms. Preferably, the compounds are diethers having an average of about 14 to about 16 oxypropylene groups as such compounds have very good lubricating properties at elevated temperatures and have superior hydrolytic stability. Suitable polyoxypropylene compounds are available commercially, two such being Ucon DLB-ZOOB and DLB-14OE, diether products of Union Carbide.

The non-ionic surface-active condensate of ethylene oxide may be selected from the many such compounds known to the art. The amount used should not exceed about 30 percent by weight based on the weight of the composition. Amounts appreciably larger than about 30 percent result in deleterious interactions with the dip applied to the cords in use and lead to loss in adhesion. Further, higher concentrations of surface active agents increase finish wash-01f during application of the aqueousbased adhesive dip, thus contributing to lower fatigue resistance caused by inadequate interfilament lubrication. In general, the amount of surface-active agent will be between 5 and 15 percent by Weight since these concentrations promote good adhesion and do not result in a loss of fatigue resistance. Preferred surfactants are those formed by the condensation of from about 10 to about 15 molecular proportions of ethylene oxide with one molec ular proportion of either a fatty alcohol, fatty acid or alkyl phenol containing about 12 to 20 carbon atoms. Other suitable surface active agents may be prepared by condensing ethylene oxide with polyols followed by partial esteriflcation or by condensing ethylene oxide with the partial esters of polyols. In these, as well as with those condensates previously mentioned, suitable results may be obtained by using from about 5 to about 40 molecular proportions of ethylene oxide for each molecular proportion of the OH-bearing organic compound. Of course, mixtures of surface-active materials may be used provided the total amount does not exceed 30 percent, by Weight, of the composition.

Antioxidants suitable for use with polyoxyalkylene materials are known to the art. There may be mentioned, for example, the aryl amines, particularly the N-aryl derivatives of aryl amines, alkylene-bis-phenols and thio-bisphenols as well as mixtures thereof and the like. Some of these antioxidants are more effective than others and their use in compositions exposed to an oxidative atmosphere at elevated temperatures is a highly preferred embodiment of this invention. As specific materials there may be mentioned a condensation product of diphenyl amine and acetone such as Aminox sold by Naugatuck Chemicals Co.; 4,4-thio bis(2-methyl-5-t-butyl phenol); and a polymer of 1,2-dihydro-2,2,4-trimethyl quinoline. For example, the amine-acetone condensation product is more than 3 times as elfective as N-phenyl-u-naphthylamine in a 30-second exposure at 218 C. at a level of 0.5%, by weight. Under some conditions, such a highly effecltive antioxidant may be necessary to obtain optimum resu ts.

The compostions of this invention are especially suited to the production of tire yarns in high temperature proceses. In these processes wherein the yarns are drawn and/or annealed at elevated temperatures, the composition of this invention provides tire yarns having a high level of adhesion and resistance to fatigue and which can be produced continuously at a high level of quality. Further, these yarns are resistant to the generation and accumulation of static, and are easily wetted by the aqueous dip required in cord manufacture and thus provide improved adhesion even when low dip levels or sensitive adhesive systems are encountered.

The yarns useful in the practice of this invention are of nylon such as polyhexamethylene adipamide, polycaproamide, the reaction product of dodecane dioic acid and bis-(p-aminocyclohexyl) methane or their amide forming derivatives, melt-blend nylons such as those described in British Patent 918,637 or other nylon or copolymer thereof. All such nylons are well known and are described in the patent literature to which reference can be made.

Typical equipment that may be used in practicing the present invention is shown schematically in the accompanying drawing to which reference now will be made. In practice, nylon filaments issue from a spinneret and pass across the face of a finish roll 12 which rotates partially submerged in a lubricating composition of the invention contained in a trough 13. The lubricating composition is applied at an elevated temperature, e.g., 80 to 120 C., to facilitate the application of a uniform coating to filaments of the yarn. The coated filaments are converged to form a yarn 14 which is forwarded about feed rolls, 15 and 16 in multiple wraps, and passes around a snubbing pin 17. Roll 15 is the driven roll and 16 is a separator roll. A first stage draw roll 18 is operated at a surface speed higher than that of feed roll 15 whereby the yarn is drawn to a specified extent in the first stage while snubbed around pin 17. Yarn leaving driven draw roll 18 and its associated separator roll 19 passes about tube 20, internally heated by current supplied through leads 21 and 22, whereby the yarn is raised to the desired temperature and is subjected to drawing tension applied by driven rolls 25 and 26 located in an annealing chest 23. An additional amount of drawing takes place in this second-stage draw zone. The yarn is wrapped a number of times about rolls 25 and 26 whereby it is held at an elevated temperature and a constant length to anneal it. Heat can be supplied to the chest 23 by a hot air duct 24. Since the yarn 14 is hot as it leaves chest 23, it will retract spontaneously if given the opportunity to do so. This opportunity is provided by operating driven roll 27, and its separator roll 28 at a lower peripheral speed than rolls 25 and 26, thus permitting the yarn to relax a predetermined amount. Since rolls '27 and 28 are not intentionally heated, the yarn is quenched by contact therewith, largely preventing further retraction in subsequent handling steps. Yarn leaving rolls 27 and 28 is passed through a guide 29 and woundup to produce a package 30 on a conventional Windup, such as a surface-driven no-twist windup.

All of the apparatus used is well known and other known equipment can be substituted if desired. For example, pinch rolls, or two driven rolls may be used in place of the feed rolls 15 and 16. Any snubbing pin or suitable snubbing device may be used instead of pin 17, as long as the draw point is localized substantially on the snubbing device. Multiple pins, two for example, may be employed about which the yarn passes in an S wrap. It is usually unnecessary to heat the snubbing element, since yarn friction normally produces enough heat to attain a satisfactory drawing temperature; pin temperatures of 20 to 85 C. are satisfactory, 50 to 85 C. being preferred.

It will be apparent that first-stage draw roll combination 18, 19 may be as indicated, or both rolls may be driven. Alternatively, roll combination 18, 19 may be dispensed with, and a satisfactory distribution of draw ratio between the first and second stage obtained by adjusting the relative amount of snubbing on elements 18 and 20, and the temperature of element 20. As a guide in providing satisfactory distribution of draw ratio for such an arrangement, it should be noted that increased snubbing on pipe 20 will increase the proportion of draw in the second stage and simultaneously reduce the draw occurring in the first stage at pin 17. An increase in temperature of pipe 20 will also increase the draw ratio in the second stage, as it reduces the tension required for drawing in that stage. Alternatively, the use of a hot plate (reduced snubbing) instead of the pipe will reduce the draw ratio in the second stage.-

Heating element 20 is preferably an internally heated pipe as stated above; the pipe may be heated electrically or by hot oil, hot air, steam, or the like. It may also be replaced by a hot plate, a radiant tube, a bath containing hot liquid, or other suitable yarn heating device. Annealing chest 23 is used to maintain the yarn and its associated drawing rolls 25 and 26 at an elevated temperature; usually this will be about the same as pipe 20. It will often be necessary to supply the heated enclosure with hot air at a temperature higher than that which it is desired that the yarn will attain; for example, air at 240 C. may be suitably employed to anneal the yarn at 215 C. The number of wraps on rolls 25 and 2 6 and their peripheral speed will determine the length of time the yarn is maintained at the elevated temperature. Preferably, this should be for a time of 0.25 to 0.60 second. In place of the heated chest, the yarn may be passed repeatedly over a hot plate-roll combination, or over internally heated rolls or the like.

The use of unheated relaxing rolls, 27 and 28 permits a controlled amount of yarn retraction, and also serves to cool the yarn to a temperature near that of the environment, thus stabilizing it for further processing. However, it will sometimes be possible to eliminate rolls 27 and 28, when the windup is of the type which winds the yarn at a constant linear rate. This rate should be adjusted to permit the yarn to retract the required amount. In general, tension in this zone should be of the order of 0.2 to 1.5 grams/denier.

A windup for the yarn can be any of the known devices suitable for this purpose. A surface-driven windup is highly suitable; the yarn may be traversed onto such a package by a cam, moving lever, grooved roll or the like. Alternatively, a conventional ring twister windup may be employed. In general, the yarn will be woundup at speeds of 1,000 meters per minute and more.

The drawn and annealed yarns of this inventio are converted to cords for the reinforcement of rubber tires in a manner well known to those skilled in the art. Generally, the yarns are twisted and plied to a cord structure and the cord passed through an adhesive dip bath containing a resorcinol-formaldehyde-latex (RFL) type dip. The amount of dip applied will commonly be between 2 and 7 percent and preferably 4 to 6 percent, by weight, based on the total weight of the yarn. The cords are dried during a hot-stretching step following dip application.

The cords are molded into test specimens, using a rubber tire carcass stock for a U-pull test or are molded into standard 0.25 x '0.25-inch H-pull test specimens. As desired, the stock may be of natural, SBR, natural-SBR type and the like. After removal from the mold, adhesion is determined by measuring the force required to separate the cord from the rubber. The measurement may be made at room temperature or at an elevated temeprature and the force required for separation is reported in pounds. Cord fatigue life is determined by the test described in ASTM Method D885. In this test, the specimen is subjected to alternating compression and tension forces and the fatigue life is the number of cycles (commonly kilocycles) required to cause failure. I

In the examples which follow, all parts are by weight and all percentages are by weight, based on the total weight of the components.

Example 1 A lubricating composition is prepared by mixing 89.5 parts of a polyoxy 1,2-propylene ethyl, butyl dietherhaving an average molecular weight of about 1,014 (about 16 oxy-l,2-propylene units), 10.0 parts of the monolaurate of polyoxyethylene glycol having an average molecular weight of about 590 and 0.5 part of N-phenyl-u-naphthylamine. The composition is heated 'to a temperature of C. and is applied to a freshly-spun polyamide tire yarn by a roll rotating in a trough containing the composition. The yarn, which contains 1% of the lubricating composition, is then led to a first-stage draw zone where it is colddrawn. The yarn then passes to a second-stage draw zone where it is hot-drawn to a residual elongation of about 16% by passing in a helical wrap about a tube heated to a temperature of 180 C. The draw rolls of the second stage are heated to a temperature of about 225 C. to anneal the yarn. The drawn and annealed yarn then passes to tension let-down rolls, and thence to a high speed windup where the yarn is packaged. A high quality yarn is produced continuously in this manner for more than 3 weeks without work stoppage due to fouling of the heated surfaces. An 840-denier 140-filament yarn is produced in this manner from a melt-blend hexamethylene adipamide/hexamethylene isophthalamide 87/13 copolymer. Portions of this yarn are then used to prepare test specimens in the conventional manner in natural rubber and natural-SBR-type rubber stock which are used in the previously described adhesion and fatigue tests. The cords contain 5% of an RFL dip and adhesion is measured at 140 C. The data obtained are: hot adhesion (lbs.), 52.4 in natural rubber stock for U-pull; fatigue life (kilocycles), 647 and hot adhesion (lbs.) of 23.0 in natural- SBR-type rubber stock for H-pull.

These data show that use of the lubricating composition according to the present invention results in excellent fatigue life and hot adhesion. This is quite surprising because the use of closely related polyglycols has resulted in poor adhesion or inferior resistance to flex fatigue.

Example 2 The process described in Example 1 is used to prepare a 1260-denier 2l0-filament yarn containing 1.3% of a lubricating composition. The lubricating composition is prepared from 88 parts of the lubricant and parts of the surface-active condensate of Examples 1 and 2 parts of a polymer of 1,2-dihydro-2,2,4-trirnethyl quinoline as the antioxidant. Portions of this yarn are then used to prepared test specimens in the conventional manner which are used in the previously described H-pull adhesion test on natural-SBR-type rubber stock. A control yarn and specimens are prepared in like manner except that the lubricating composition is applied at 75 C. The control yarn contains 1.1% of a commercially used lubricating composition in which the lubricant is coconut oil and the antioxidant is a condensate of diphenyl amine and acetone. The yarn containing the composition of this invention has a hot adhesion value of 18.3 lbs. and the hot rolls operate for more than three weeks before requiring cleaning. The control yarn has a hot adhesion of 17.6 lbs. and requires cleaning after 3 days of operation.

Example 3 Example 2 is repeated except that the yarn contains 1.4% of a lubricating composition consisting of 78 parts of the lubricant, parts of the surface-active condensate and 2 parts of the antioxidant of Example 1. The results are similar to those of Example 2.

While the invention has been described with reference to particular materials and quantities, it will be appreciated that these details are merely representative and that changes therefrom can be made without departing from the scope of the invention.

- What is claimed is:

1. Tire cord yarn composed of nylon filaments having on the surfaces thereof about 0.3 to 3 percent by weight, based on the weight of the resulting yarn, of a nonaqueous lubricating composition consisting essentially of about 70 to 97 parts of a polyoxypropylene compound of the formula R(OC H OR' where R and R are selected from the class consisting of alkyl and acyl groups having 1 to 4 carbon atoms and x has an average value of about 10 to 20, about 3 to 30 parts of a nonionic surface-active condensate of ethylene oxide and up 5 parts of an antioxidant for the polyoxypropylene compound. I

2. Tire cord yarn in accord with claim 1, the polyoxypropylene compound being polyoxy 1,2-propylene ethyl, butyl diether containing about 16 propylene units, the condensate being the monolaurate of polyoxyethylene glycol having an average molecular weight of about 590 and the antioxidant being N-phenyl-naphthylamine or 1,2- dihydro-2,2,4-trimethyl quinoline.

3. A tire cord in accord with claim 2, the nonionic surface-active condensate being present in an amount of 3 to 15 parts and the antioxidant being 1,2-dihydro-2,2, 4-trimethyl quinoline.

4. A nonaqueous lubricating composition for nylon tire cord yarn consisting essentially of about 70 to 97 parts of a polyoxypropylene compound of the formula where R and R are selected from the class consisting of alkyl and acyl groups having 1 to 4 carbon atoms and x has an average value of about 10 to 20, about 3 to 30 parts of a nonionic surface-active condensate of ethylene oxide and up to 5 parts of an antioxidant for the polyoxypropylene compound.

5. A composition in accord with claim 4, the polyoxypropylene compound being polyoxy 1,2-propylene ethyl, butyl diether containing about 16 propylene units, the condensate being the monolaurate of polyoxyethylene glycol having an average molecular weight of about 590 and the antioxidant being N-phenyl-a-naphthylamine or 1, 2-dihydro-2,2,4-trimethyl quinoline.

6. A composition in accord with claim 5, the nonionic surface-active condensate being present in an amount of 3 to 15 parts and the antioxidant being 1,2-dihydro-2,2,4- trimethyl quinoline.

7. In the preparation of nylon yarn for use as tire cord in which nylon polymer is melt-spun to produce a plurality of filamentary strands, the resulting strands are coated with about 0.3 to 3 percent by weight, based on the weight of the resulting strands, the strands are collected to a yarn and the yarn is drawn and annealed and contacts highly heated surfaces, the improvement comprising using as the lubricating finish composition a nonaqueous composition consisting essentially, by weight, of about 70 and 97 parts of a polyoxypropylene compound of the formula R(OC H OR' where R and R are selected from the class consisting of alkyl and acyl groups having 1 to 4 carbon atoms and x has an average value of about 10 to 20, about 3 to 30 parts of a nonionic surface-active condensate of ethylene oxide and up to 5 parts of an antioxidant for the polyoxypropylene compound.

8. A process in accord with claim 7, the polyoxypropylene compound being polyoxy 1,2-propylene' ethyl, butyl diether containing about 16 of the propylene units, the condensate being monolaurate of polyoxyethylene glycol having an average molecular weight of about 590 and the antioxidant being N-phenyl-a-naphthylamine or 1,2- dihydro-2,2,4-trimethyl quinoline.

9. A process in accord with claim 8, the nonionic surface-active condensate being present in an amount of 3 to 15 parts and the antioxidant being 1,2-dihydro-2,2,4-trimethyl quinoline.

References Cited UNITED STATES PATENTS 2,668,785 2/1954 Jefferson et al. 117-1395 2,865,855 12/1958 Chandler 117-1395 2,964,470 12/1960 Wentworth. 3,039,895 6/1962 Yuk 117-1395 3,155,537 11/1964 Patterson et al 117-1388 3,248,258 4/1966 Coats 117-1388 HERBERT B. GUYNN, Primary Examiner.

US. Cl. X.R. 

